Lifting-jack.



F. E. PARNHAM.

LIFTING JACK. APPLICATION TILED FEB.21,1912.

036,204. Patented Aug.20,191 2 i z sums-suns: 1.

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- j Inventor:

Fred Elw n/1am m.

cflharney.

single toothed cam is engaged by a gear and f gear 1. Slidably mounted in opposite ends in section on line 6,

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FRED E. FARNIIAM, OF RUMFORD, MAINE.

marine-JACK.

1 ,036 ,204. Application filed February To all whom it may concern: 7

Be it known that I, FRED E. F AnNrr r,

a citizen of the United States, and a residentof Rumford, in the county of Oxford and State of Maine, have invented certain new ple in construction, powerful in action and readily adaptable to a variety of service.

In the drawings accompanying this specification is illustrated the preferred embodis ment of my improvements. Therein Figure 1 is a front elevation partly. in section. on line 11 of Fig. 2. Fig. '2 is a side sectional elevation on line 2 2 of Fig. 1. Fig. 3 is a front view of a detail of Fig. 2. Fig. 4. is a view similar to Fig. 2 and illustrating modifications of my improvements. Fig. 5 is a rear elevation of the lower portionof Fig. Fig. 6 is :1V plan view, partly I 6 of Fig. 4, and Fig. 7 is a front elevation of details of Fig. 1.

I am familiar with cam jacks in which a I donot broadly claim such known construction. My improvements comprise a compound cam jack in which two oppositely disposed toothed cams are engaged by one common gear whereby the lifting movement-1 is doubled within theone angle of rotation of the driving gear, theaction of the cams balanced and the shearing strain on the gear shaft substantially eliminated.

Case 3 is preferably a cylindrical tube and has rotatably mounted midway its length and transversely thereof, actuating of case 3 are plungers 5, 7 having pivotally mounted at their inner ens opposing cams as S on pin'9 of plunger 5'; Plunger 7 has similar cam 10 on pin 11. Said cams are provided with gearteeth as 12 on their peripheries for coaction with the teeth of' gear 4.- Said cam pins J and Hand gear shaft 17 lie in one plane so that shearing stress on shaft .17 is substantially eliminated and the general friction of action reduced to a minimum. Each of said cams is provided 'with a flange or opposite flanges as 13, 14:

of cam 8 concentric with its cam shaped periphery for engagement With pins as 15,

Specification 0 Letters Patent.

16 in case 3 for retaining shaft 27 in a ratchet lever wise tongue 39 thereon for ment witlrthe rear face- Patent-ed Aug. 20, 1 912.

21, 1912. Serial No. 679,025.

.id cams in engagement with gear 4. Ferotating gear 4: I may mount said gear on shaft 17 having hearings in case 3. Said shaft 17 may engage said gear by means of squared portion 18 in square hole 19 of said gear. Outboard end 20 of said shaft may also be squared to conveniently engage a wrench or crank, not shown. Said shaft may be retained in endise position by means of front plate 21 held in place by heads as 22 of screw pins as 15. Outboard said plate 21 ratchet 23 is fixed to shaft. 17 for engagement with pawl 24 pivoted. at 25 to case 3. Said ratchet and pawl are eiiicient for preventing the collapse of said jack from its extended position.

In some cases I prefer to mount modified 28- as shown in Figs. 4, 6 and 7 wherebyv when said shaft and lever are withdrawn said jack will pack into less space. In this modification I provide gear 4; with sleeve portion 26 projecting through the front of case 3 and to said projecting portion I fix ratchet 2-3. Modified shaft 27 turns freely in lever 28 and has ratchet 29 fixed at its outer end. Pawl 30 is pivot-ally mounted at 31 on lever 28 and is urged to engagement with ratchet 29 by spring 32.

In some cases it desirable to employ my improved jack in places too small to permit its insertion. In such cases I employ stirrup 33 whose inreaching head 34 has plug for engagement with socket .36 of cap 37 of plunger Said stirrup is provided with foot 38 for direct engagement with the piece to be lifted or moved. Case g has'length guiding stirrup 33 by-engagement with lengthwise groove 40. of said stirrup. I also provide said stirrup withantifriction roll 41 for rolling engage- The operation of my improved jack is as follows: Shaft 17 or 27 being rotated ina clockwise direction Fig. 1, geared cams 8 and '10 are rotatedin an a'nti clockwise direction on'their respective pivots, fixed in plungers 5 and 7 respectively; said plungers are thereby forced outwardly relative to case 3 and if lower plunger 7 is fixed in position by the engagement of its foot 42 with a fixed abutment as a floor case 3 will be moved upwardly a distance corresponding with the throw of one of cams 8, 10 and upper plunger 5 will be moved up- Wardly a distance equal to the sum of the throws of both cams 8,- 10. In rotating shaft 17 or 27 ratchet 23 will be engaged by pawl 24 whereby said plungers 5, 7 and cams 8, 10 will be prevented from running down and dropping the load. When it is desired to collapse the jack and lower the load shaft 17 or 27] is rotated in a clockwise direction sufficiently to free pawl 24 from ratchet 23, when said pawl may be swung upwardly on its pivot and the direction of rotation of shaft 17 or 27 reversed thereby lowering the load.

I claim 1. The combination in a cam jack of two opposing rotatably mounted toothed cams actuated by a common gear thereb'etween, whereby the bearingsof said gear are free of the lifted load.

2. The combination in a cam jack of a case having a gear pivotally mounted on a fixed bearing therein, a plunger slidably mounted in each end of said case, a toothed cam pivotally mounted'on a fixed bearing in each of said plungers for opposite engagement with said gear, whereby the bearings of said gear are free of the lifted load.

3. The combination in a cam jack of a case having a gear pivotally mounted on a fixed bearing therein, mounted in each end of cam pivotally mounted on a fixed bearing in each of said plungers for opposite engagement with said gear, whereby the bear ings of said gear are free of the lifted load,

said case, a toothed a plunger slidably said cam pivots and gear pivot lying c0n stantly in one plane.

' 4:. The combination in a jack, of a case, a plunger slidably mounted in each-end thereof, means for sliding said plungers relative to said case, a removable stirrup. slidably mounted lengthwise said case and means in the outer ends of said plungers respectively for engagement one stirrup.

5. The combination in a jack, of a case, a plunger slidablymounted in said case, means for sliding said plunger relative to said case, a stirrup, guiding said stirrup, means for connecting said plunger and stirrup and an anti-friction roller on said stirrup for engaging the guiding means on said case.

6. The combination in a cam jack, of a cylindrical tubular case, a pair of oppositely disposed cylindrical plungers slidably mounted. therein, transverse slots in their inner ends, a toothed cam pivotally mounted in each plunger slot, and a gear pivotally mounted between said cams in said tubularcase for simultaneous engagement with said toothed cams.

Signed atRumford, in the county of OX- ford and State of Maine, this 13th day of February, 1912, before two subscribing witnesses.

" FRED E. FARNHAM. WVitnesses:

HARO D M. IRMEs, AUSTIN E; FRISBIE.

at a time with said means lengthwise said case for said plungers having 

